SEOUL, Jan. 7 (Yonhap) -- South Korea said Thursday that it will resume anti-Pyongyang broadcasts this week along the heavily fortified border with North Korea in retaliation of Pyongyang's claimed hydrogen bomb test.

The anti-Pyongyang broadcasts will resume at noon on Friday, Cho Tae-yong, deputy chief of the presidential office of national security, told reporters.

"The North's fourth nuclear test is a grave violation" of the August deal, Cho said, referring to a breakthrough deal that defused heightened tension sparked by a land-mine blast near the inter-Korean border blamed on North Korea.

The move could further escalate tensions with North Korea, which had threatened to launch "strong military action" against loudspeakers blaring messages critical of North Korean leader Kim Jong-un.

Cho said South Korean troops maintain combat readiness and will sternly retaliate against North Korea if Pyongyang stages a provocation.

"North Korea could carry out a surprise provocation at any time in the current confrontational situation on the Korean Peninsula and we should be prepared for it," President Park Geun-hye said in a meeting with nearly 500 female leaders in western Seoul.

South Korea and the U.S. are in talks on how to deploy strategic U.S. military assets in South Korea in a show of force to deter any possible North Korean provocations.

In August, South Korea resumed the propaganda broadcasts along the border for the first time in 11 years in retaliation for the North's land-mine attack that maimed two South Korean soldiers.

In return, North Korea gave a 48-hour ultimatum to South Korea to end the propaganda broadcasts and dismantle all loudspeakers, saying it otherwise will launch "strong military action."

The two sides later held days of intensive high-level talks and produced a deal in August, in which South Korea agreed to stop propaganda broadcasts unless an abnormal situation occurs.

South Korea views North Korea's nuclear test as an abnormal situation.

North Korea has repeatedly called for the end of the broadcasts, viewing them as an insult to its dignity. The isolated country is also concerned that an influx of outside information could pose a threat to its young leader.

"There is a high possibility that North Korea could react in an ultra-harsh manner by regarding South Korea's decision as ruining the birthday celebration," said Cheong Seong-chang, a senior researcher at the Sejong Institute.

The resumption of anti-Pyongyang broadcasts coincides with Kim's birthday, which falls on Friday.

Also Thursday, Park held a telephone conversation with U.S. President Barack Obama and they agreed to closely cooperate to ensure that the U.N. Security Council can adopt a resolution for strong sanctions on North Korea over its hydrogen bomb test, Cheong Wa Dae said.

The two leaders also shared the view that the international community must make sure that North Korea pays the corresponding price for a nuclear test, the South Korean presidential office said.

In Washington, the White House said Obama reaffirmed the "unshakable U.S. commitment" to South Korea's security, and the two leaders agreed to work together to forge a united and strong international response to North Korea's latest reckless behavior.

"The two leaders condemned the test and agreed that North Korea's actions constitute yet another violation of its obligations and commitments under international law, including several U.N. Security Council Resolutions," the White House said in a statement.

The U.N. Security Council held an emergency session on Wednesday and agreed to immediately start work on a new sanctions resolution against North Korea. The council "strongly condemns" Pyongyang's latest nuclear test.

North Korea has already been under U.N. sanctions for its three previous nuclear tests in 2006, 2009 and 2013.

Park and Obama also shared the need of coordinating a stance with China in dealing with North Korea's hydrogen bomb test.

Chinese support is crucial in adopting a new resolution for sanctions as it is one of the veto-wielding five permanent members of the council. The four other members are the U.S., Britain, France and Russia.

China is a traditional ally of North Korea and is believed to have significant leverage over North Korea, but Pyongyang's latest nuclear test showed that Beijing's influence is limited.

The bilateral ties -- once described as being as close as "lips and teeth" -- have been strained over the North's defiant pursuit of nuclear ambition.

Park also spoke with Japanese Prime Minister Shinzo Abe and they agreed to closely work together for the swift adoption of a U.N. resolution for strong sanctions on North Korea.